dts: Improve readability of DT_xxx_M macro

Change '(x) * num' to reuse DT_xxx_K macro.

Signed-off-by: James Roy <rruuaanng@outlook.com>

dts/common/freq.h

@@ -8,6 +8,6 @@
 #define __DT_FREQ_H
 
 #define DT_FREQ_K(x) ((x) * 1000)
-#define DT_FREQ_M(x) ((x) * 1000 * 1000)
+#define DT_FREQ_M(x) (DT_FREQ_K(x) * 1000)
 
 #endif /* __DT_FREQ_H */

dts/common/mem.h

@@ -8,7 +8,7 @@
 #define __DT_MEM_H
 
 #define DT_SIZE_K(x) ((x) * 1024)
-#define DT_SIZE_M(x) ((x) * 1024 * 1024)
+#define DT_SIZE_M(x) (DT_SIZE_K(x) * 1024)
 
 /* concatenate the values of the arguments into one */
 #define _DT_DO_CONCAT(x, y) x ## y